Ignition harness



June 29, 1943. H. M. wlLKoFF IGNITION HARNESS Filed Deo. 27, 1940 2Sheets-Sheet l June 29, 1943. H. M wlLKoFF 2,322,903

IGNITION HARNESS Filed Dec. 27, 1940 2 Sheets-Sheet 2 Patented Jeune 29,1943 UNITED STATES PATENT OFFICE IGNITION HARNESS Howard M. Wilkofl',Worcester, Mass.

Application December 27,1940, Serial No. 371,927 n (ci. 174-71) 15Claims.

This invention pertains to ignition harness for internal combustionengines and to a method of making such harness.

An ignition harness is made up of the various ignition wires leadingfrom the distributor of the internal combustion engine to the sparkplugs. While the invention maybe of more general utility. it isvespecially designed asan improvement in the harness used in airplaneengines. In some of these engines the cylinders are radially disposedandfsome have a straight-.line arrangement and the improved harness isapplicable to both types of engine.

Considering the radial engine as an example, the harness usuallycomprises an annular tubular casing which is arranged to extendconcentrically with theengine shaft and into which lead the conductorsfrom the magneto or magnetos.

the conduit and then through the connection at the other end of theconduit before they can be connected to the spark plug terminal. If donecarefully, this operation may be performed without injury to theconductor, but when repairs must be made by those who are not especiallyskilled or careful, the insulation may be scraped off or injured inpulling the conductor through the irregular channel provided for it, andnot only may the particular conductor thus drawn in be injured but theoperation may likewise injure the insulation of some of the otherconductors already in place. Moreover, since airplane engines areordinarily provided with double ignition systems, it may happen that ifone of the conductors belonging to one of these systems should breakdown so as to emit sparks within the manifold, its failure may not benoticed during operation of the engine since the other ignitionsystemprovides for this emergency, and thus before the defect is discoveredthe sparking may have seriously injured those art, the ignitionmanifold) to the spark plug of one of the respective cylinders. Theconductors thus extend todiferent distances around t"e circumference ofthe manifold and the manifold maybe of gradually decreasing transversearea. or may be of uniform` cross section throughout its lengthaccordingto the choice of the designer. l

In certain common types of harness the manifold is made of flexible'tubing and each conductor extends continuously from the magneto to itsrespective spark plug. In order to protect the conductors frommechanical injury and to avoid radio interference, it is necessary thateach individual conductor be enclosed within metal from the time itleaves the generator until it connects with the spark plug terminal. tieignition manifold is made of metal or is to the manifold to which isconnected a conduit, usually flexible, which encloses the conductor andwhich extends to the spark plug to which itis secured by a specialconnection.r

The conductors used for this purpose, particularly for army and navyuse, are very finely constructed,."being provided with insulation of thehighest quality and are usually covered with a coating of lacquer.However, these finely finished conductors must be put in place in theharness by drawing them in at one end of the maniof the conductor withinthe manifold may be electrically connected to the ignition wire whichleads from the outlet fitting through the conduit to the spark plug. Inthis latter form of manifold it has been proposed permanently to embedthe several conductors which are arranged within it in a body ofvinsulating material which is poured into the manifold casing after theas- 40' encased with metal and where each conductor leaves the manifoldan outlet fitting is secured' sembled conductors have been put invplace. However, difiiculty is experienced in fllling the manifold casingwith an insulating medium of appropriate type. Thelacquer used at theouter surface of the several conductors may be seriously 1 injured byany solvent which would make the insulating medium sufficiently uid toow at normal temperatures into the manifold. Likefold, thence part wayaround the manifoldand wise if such a solvent be employed it isdifficult to provide for its evaporation from the closed interior of themanifold within any practical period of time. On the other hand, if theinsulating material be thermoplastic and be heated sufliciently tosoften it, `the temperature requisite may be such that the heatedinsulating material will injure the individual conductors, for exrubbercovering with consequent loss of insulating value. Moreover, since theinsulation material which is placed in the manifold must not be brittleat arctic temperatures and must maintain its shape and insulatingproperties at temperatures to which it may be exposed in the tropicswith the engine running, it is difficult to find such a medium which maybe flowed into the manifold cavity.

It has also been proposed to encase the conductors in a Jacket of rubberand, after vulcanizing the latter, to house the rubber-lacketed cablesin the outer metallic casing, but the application of heat sufficient tovulcanize the mass of rubber forming the Jacket is injurious to theinsulation of the individual conductors and may so decrease thedi-electrlc strength of such insulation as to result in an earlybreakdown and sparking under conditions of use.

A principal object of the present invention is to provide an improvedignition manifold of the kind in which the conductors are permanentlyfixed within the manifold casing and comprising an integral jointlessjacket of oil and moisture resistant insulation of adequate thickness inwhich the assembled conductors are embedded. A further object of theinvention is to provide an improved ignition harness comprising amanifold, and conduits leading therefrom to the several spark plugs, andwherein the individually insulated conductors within the manifold andwithin the respective conduits are encased in a continuous iointlessinsulating jacket of a highly elastic, oil, gasoline, and Waterresistant material capable of withstanding extremes of temperature,vibration and shock without mechanical breakdown and which is of highdielectric strength. A further object of the invention is to provide animproved ignition harness comprising a manifold and conduits leadingtherefrom to the several spark plugs and wherein the conductors withinthe manifold and within each conduit are each encased in a metalsheathing interposed between concentric bodies of insulation, suchsheathing having the two-fold function of preventing radio interferencefrom the high tension current pass ing through such conductors, and ofpermitting the heat treatment f the jacket of insulating material inwhich the conductors are embedded without injuriously heating theinsulation of the individual conductors.

A further object of the invention is to provide a method of and novelapparatus useful in the making of such ignition harness and theconstituent parts thereof and in particular to provide a method wherebyan individually insulated conductor or conductors may be jacketed withan insulating substance which requires heat treatment in its applicationbut without so heating the insulation of the individual. conductor as toinjure its mechanical or di-electric qualities.

A further object is to provide an improved method whereby, afterwrapping an individually insulated conductor or conductors withthermoplastic insulating material to form a plurality of concentriclayers, heat may be applied (or in fact, generated) in such a Way as toheat said layer or layers sufficiently to permit consolidation andintegration thereof without injuriously heating the insulation of theconductor or conductors.

Other and further objects and advantages of the invention will bepointed out in the followaaaaaoa' ample by causing an over-vulcanization'of the ing more detailed description and by reference to theaccompanying drawings, wherein Fig..1 is a diagrammatic frontelevationof a harness for a radial type engine, certain oi the ignitionwires being broken away, only one of the spark plugs being illustrated;

, Fig. i* is a detail section to large scale, illustrative of apreferred form of fitting at the Juncirn of one of the ignition wireswith the mani- Fig. 2 is a fragmentary elevation, partly in diametrica]section, illustrating one of the conductors which is comprised in theignition manifold:

Fig. 3 is a section on the line I-l of Fig. 2;

Fig. 4 is a fragmentary elevation illustrating a plurality of theconductors arranged to form a cable-like assembly;

Fig. 5 is a section on the line B-S of Fig. 4:

Fig. 6 is a fragmentary elevation showing the assembly of Fig. 4 afterhaving its outer surface made smooth and substantially cylindrical;

Fig. 7 is a section on the line 11 of Fig. 6;

Fig. 8 is a fragmentary elevation illustrating the step of applying athin, flexible metallic sheathing to the structure of Fig. 6;

Fig. 9 is a section on the line 9--8 0f Fig. 8;

Fig. 10 is a fragmentary perspective view illustrating an oil andmoisture resistant thermoplastic insulating tape useful in providing aninsulatlng jacket for the assembly shown in Fig. 8;

Fig. 11 is a fragmentary elevation illustrating the step of applying theinsulating jacket to the assembly of Fig. 8;

Fig. 12 is a section on the line I2-I2 of Fig. 11;

Fig, 13 is a vertical section diagrammatically illustrating a multi-partmold device and showing in section fragmentary portions of a presswhereby pressure is applied to the mold parts;

Fig. 14 is'a plan view of the lower part of the mold of Fig. 13;

Fig. 14 is a similar plan view 0f a mold part having a mold cavity of adifferent formation;

Fig. 15 is a diagrammatic plan view of the mold of Fig. 13 andillustrating means for supplying heat to the wrappings of insulation;

Fig. 16 is a fragmentary elevation illustrating the composite assemblyresulting from the use of the apparatus of Fig. l5;

Fig. 17 is a section on the line ll-I 'I of Fig. 16;

Fig. 18 is a fragmentary section showing the structure of Fig. 16provided with an outer protective casing; and

Fig. 19 is a section on the line I9--i 9 of Fig. 18.

Referring to the drawings, the numeral I designates an ignition harnessof the general kind employed for engines of the radial type. Thisignition harness comprises the substantially circular ignition manifold2 which comprises an external protective casing, usually of metal, andwhich is provided at regularly spaced intervals with fittings 3 to eachof which is connected one end of a conduit 4, through which runs anignition wire 4B (Fig. 1*) extending to one of the spark plugs S. Theouter casing of the manifold houses a plurality of individuallyinsulated conductors 6, one` end of each conductor being secured to oneof the terminals respectively of one of the magnetos 1. The severalconductors 6 are of different lengths, one of such conductorsterminating adjacent to each of the fittings 3. Each fitting 3 (Fig. la)is provided with means for mechanically securing to it the outerprotective conduit 4 of one of the ignition wires 4, and also hasprovision for electrically connecting the end of the metallic core of aconductor i to the ignition wire 4 in the conduit 4.

, As illustrated in Figs. 2 and 3, each conductor 6 comprises a metallicconducting wire or core I and insulation 9 which may, for example, be ofrubber, braid, lacquer or resin.

In making the manifold, in accordance with the present invention, it ispreferred to cable-lay the several conductors 6 so that they twine abouteach other in helical turns as shown in Figs'. 4 and 5. The severalconductors 6 making up the cablelike assembly thus provided are ofdifferent lengths as above suggested. For use as herein specificallyillustrated merely by way of example, one end of each conductor maybearranged near one end of the assembly, said ends being those which areconnected to the magneto terminals, while the opposite ends of theseveral conductors are arranged each to terminate adjacent to one of thefittings 3 of the manifold when the parts are assembled. Since thenumber of conductors making up the cable-like assembly thus decreasesfrom point to point along the manifold, the outer casing of the manifoldmay be made correspondingly to diminish in transverse .dimensions or,alternatively, it may be of uniform transverse section and the space maybe filled by the use of dummy conductors which take the place in thecable of the true conductors beyond the points where the latterterminate at the several fittings.

After having thus cable-laid the conductors 6, a substantially circulartransverse section is preferably then imparted to this assembly ofconductors by winding insulating material, for example, a speciallytreated asbestos yarn or properly shaped extruded strands of plasticmaterial into the helical grooves III extending around the cable.However, any other suitable method of providing a circular section andsubstantially smooth cylindrical outer surface II (Figs. 6 and 7) may beemployed. Having prepared this assembly with its substantiallycylindrical and smooth external surface, the next step is to encase itin a flexiblemetallic sheathing, forexample, a wrapping of thin metalribbon I2 (Figs. 8 and 9). This Wrapping may, for example, be ofDuralumin foil of approximately 0.0015 inch thick wrapped helicallyabout the cable so as to overlap one-half its width, thus providing acomplete metal sheathing I3, Fig. 9. Alternatively, the assembly mightbe drawn into a tubular metallic casing.

After applying this metal sheathing, the sheathed cable is Wrapped withtape Il (Fig..10)' of a thermoplastic character. Preferably this tape ismade of one of the vinyl chloride or vinyl acetate resins, for instance,a polymerized vinylv chloride, such tape being, for example, 0.008 inchthick. Such a tape isa commercial product employed in the automobileindustry for wrapping conductors and is of very great elasticity andtoughness throughout a wide range 'of`temperatures; it is oil andgasoline resistant (a matter of high importance when it is to be used inthe vicinity of an airplane engine or the like) and has high di-electricproperties.

concentric layers, for example, as many as twelve layers. Preferablysuccessive layers I are of op.- posite pitch. i

In preparation for the next step, suitable moldf ing means is provideddesigned ,for the simultaneous application of heat and pressure therebyto integrate the several turns and layers oi' tape, the heat being soapplied (or in fact genplemental plates 30h and 3ib respectively whicherate'd) that the layers of tape are heated substantially uniformly andalmost instantaneously, but without injuriously heating the insulatingcoverings of the several conductors. The molding means may comprise amold vconsisting of two or more separable parts II and I8 and is ofinsulating material, for example, wood, the several parts, when`operatively assembled, collectively dening a mold cavity I9 of variabledimensions and which is of proper shape to receive a portion at least ofthe wrapped cable already described. The interior of the mold cavity islined with metal foil 20, for example, tin, the mold parts beingprovided with accessibly located binding posts 2| or the like with whichthe metallic lining 20 is electrically connected and to which electricalconductors as hereafter described may be attached. Provision ismadewhereby the assembled parts of the mold may be pressed toward eachother thereby to press .the wrapped cable assembly in a substantiallyradial direction. As illustrated in Fig.'13,Y the upper and lower moldvmembers I1 and I8 are slightly separated, as they may be when the cableassembly is first introduced into the mold cavity I9A between them. Thelower mold member I8 is shown resting upon *a fixed support 22 while thevertically movable platen 23 of a power press rests upon the upper moldmember I1 in readiness to apply'downward.

ressure to the latter. -That section of *the sheathed and wrapped cablewhich extends between one of the projecting ends o f a conductor 6 andthe next, is disposedv Within the mold cavity I9 and the mold parts arethen placed under compressive stress so as radially to compact thelayers of wrapping material. Before applying pressure, the metal lining20 of the mold cavity is connected into a high frequency circuit so asto constitute one condenser plate while the tape covered metal sheathingI3 of the cable is made to constitute the other condenser plate.

`The numeral 24/J Fg. 1.5) designates the tank coil ofv a well knowntype of high frequency circuit, having prov'sion for tuning the circuit.

This coil forms the primary of which the coil 25 forms a secondary, andreceives high frequency current from the timed circuit, for examplc, ofapproximately 20,000.000 cycles. This high frequency current isconducted through vthe high frequency cable 26 to the primary 21 of aresonant circuit whose seccnary 28 hasits terminais connected to avariable condenser 2 9 and alsoto auxilary condensers `30 and 3|respectively.l Each of these condensers 30 and 3l comp.ises a plate 30and 3l respectively and comare connected to and with` the mold lining 2land the sheathing III respectively, constitute condenser platesVcorriplefzental to plates 30, 3|* resrecivelv. lished between. thesecondenser elements and ii y the material vforrrilngthe wrappings besubjected `II5v This .time lis wrapped in overlapping spirals and inv`several.

to suchhi'gh frequencyfforaperiod of 45 seconds whilcthe moldj parts'Lare under pressure, the several vlayers: I5,V of the synthetic resintape are coalevcfed vso asv to form an. integrated tubular jacketAIPF'without crevice or scam. The jacket thus provided is waterproof,oil resistant, highly elastic, `and tough and substantially unaffected`by any of the temperature conditions to vwhich the ignition manifold cfan airplane engine is ever subjected. This jacket I5l (Fig. 19) alsoprovides very effective insulation while themetallic sheathing I3 uponwhich this jacket is A. hirh frequency field is estabbuilt formseffective means to prevent. radio interferences from the high tensioncurrent passing through the conductors forming the cable as well as toenable the heat treatment of the jacket as just described withoutheating the conductors 8.

Each of the leads I from the several fittings to the respective sparkplugs may be prepared in the same way as just described except that eachof these individual leads (Fig. 1) contains but a single insulatedignition wire Ia. This single insulated wire Ia is provided with a metalsheathing I3L and is wrapped with insulating thermoplastic tape which isconsolidated by pressure and high frequency heat to lform the jacketI5'L as already described, and this jacket is then enclosed in afiexiblemetallic protective casing 32', having a connection 32D at oneend for engagement with one of the fittings 3 of the marilfold andhaving a rigid connection 32c at its opposite end (Fig. l) for unionwith the spark plug I.

After each section of the sheathed and wrapped cable has been subjectedto heat and pressure in the mold I1, I3 as above described, a fitting Iis applied at each point where the end of one of the conduits 6 projectsoutwardly from the jacket I5. As illustrated in Fig. l, each fitting 3comprises a screw-threaded portion 3x for mechanical engagement with theinternally screwthreaded connection 32b of the ignition wire conduit,the fitting also including a flange 3y which is placed in contact withthe outer surface of the jacket I5 and is bound down to the jacket by aplurality oi wrappings of the tape II, rI'his portion of the jacket I5,to which the fitting is thus bound, is now placed in a mold IIIL havinga metal lined cavity I9, I9b of suitable shape, for instance as shown inFig. 14a, the metal lin-l ing being connected to the binding post 2l,and these wrappings of tape are consolidated so as to, form an integralmass lim permanently uniting the part 3x to the jacket I5. while at thesame time adjoining sections of the jacket I5 are thoroughly integrated.

As already described, the manifold cable and the individual ignitionwires are encased in any appropriate type of outer protective covering,for example, a helically wound metallic tape, such as that employed inelectrical conduits; a braided metallic tube 32A (Fig, 18); or a sheetmetal housing, but preferably such metallic caslngs should be so appliedas to fit very snugly about the jacket and actually exert some degree ofradial stress upon the enclosed material, thus to avoid any possibilityof air spaces Within the -casing and providing against creeping of thefold comprising a flexible, seamless insulating jacket of oil andwater-resistant material having high dielectric strength and which istough and highly elastic, the manifold having a plurality of spacedfittings, fixedly anchored to the jacket, for the attachment of ignitionwires, an ignition conduit, including an ignition wire, removablyattached to each fitting, a hollow, flexible metallic sheathconstituting a lining for the insulating jacket, and a plurality ofindividually insulated conductors housed within said metallic sheath,said conductors being of different lengths and each terminating Aat oneof the respective fittings.

2. Ignition harness including a flexible manifold comprising a flexible,seamless insulating jacket of oil and water-resistant material havinghigh dielectric strength and which is tough and highly elastic, themanifold having a plurality of spaced fittings, fixedly anchored to thejacket, for the attachment of ignition wires, a hollow, flexible metalsheath fitting snugly within the insulating jacket, and an assembly ofcable-laid, individually insulated conductors housed within said metalsheath, said conductors being of dlr ferent lengths and each terminatingat one of the respective fittings, a flexible protective casing tightlyembracing the jacket, and an ignition conduit, including an insulated,radio-shielded ignition wire, mechanically connected to each fitting,each ignition Wire being electrically connected to one of the respectiveconductors within the manifold, said mechanical and electricalconnections being so designed and arranged as In permit each individualignition conduit to be detached as a unit from the manifold.

3. Ignition harness including a flexible manifold comprising a flexible,seamless insulating jacket of oil and water-resistant material havinghigh dielectric strength and which is tough and highly elastic, themanifold having a plurality of spaced fittings, lixedly anchored to thejacket, for the attachment of ignition wires, a hollow, :flexiblemetallic sheath coaxial with and which is embraced by the insulatingjacket, an assembly of individually insulated conductors within saidhollow sheath, and means imparting a substantially smooth exteriorsurface to said assembly of conductors thereby to provide snug contactof the assembly with the interior of the sheath, the several conductorsbeing of different lengths and each terminating at one of said fittings,respectively.

4. Ignition harness including a flexible manifold closed at its end andcomprising a flexible, seamless jacket of oil, water andgasoline-resistant synthetic resin having high dielectric strength andwhich is tough and elastic, the manbe limited to these preciseembodiments but is ifold having a plurality of spaced fittings flxedlyanchored to the jacket for the attachment of ignition wires, anassemblyof cable-laid, individually insulated conductors within thejacket, said conductors being of different lengths and each terminatingat one of the respective fittings, dummy conductors which take theplace, in the assembly, of the true conductors beyond the ends ofthe-latter, a hollow, flexible sheath of metal foil which snuglyembraces the assembly of conductors and which is snugly embraced by theinsulating jacket, and insulation filling the space within the sheathwhich is not occupied by the conductors, and a flexible protective outercasing tightly embracing the jacket.

5. Ignition harness including a flexible manifold comprising a flexible,seamless insulating jacket of oil-resistant synthetic resin having highdielectric strength andwhich is tough and highly elastic, the manifoldhaving a plurality of spaced fittings iixedly anchored to the jacket forthe attachment of ignition wires, a hollow, flexible sheath of metalfoil coaxial with and which is snugly embraced by the insulating jacket,an assembly of helically disposed individually insulated conductorswithin Said hollow sheath, and strand-like elements filling the helicalgrooves in the periphery of said assembly of conductors thereby toimpart a substantially smooth cylindrical peripheral surface to saidassembly, said smooth surface fitting tightly against the metal sheath,the several conductors being of different lengths and each terminatingat one of said fittings, respectively. l

6. Ignition harness including a flexible manifold of normally arcuatecontour, closed at one end and including a flexible, unitary, seamlessresilient jacket of oil, water and gasoline-resistant insulatingmaterial, the manifold having a plurality of spaced fittings, eachiixedly anchored to the jacket, for the attachment of ignition wires, anassembly of cable-laid, individually insulated conductors within thejacket, and a flexible layer of electrical conducting materialinterposed between the jacket and conductor assembly and operative toprovide a radio shield and also to constitute a condenser plate for usein the heat treatment of the jacket by high frequency current, theconductors being of different lengths and terminating at the respectivefittings.

7. Ignition harness including a flexible manifold of normally arcuatecontour, closed at one end and including a flexible, unitary vseamlessresilient jacket of oil, water and gasoline-resistant insulatingmaterial, the manifold having a plurality of spaced fittings, eachfixedly anchored to the jacket, for the attachment of ignition wires, anassembly of cable-laid, individually lnsulated conductors within thejacket, an uninterrupted flexible layer of metal foil interposed betweenthe jacket and theconductor assembly, said layer cf'foil constitutingmeans to prevent radio interference and also to act as a condenser plateuseful in the high frequency heating of the jacket material, the severalconductors being of different lengths and each terminating at one of therespective fittings, and a flexible protective casing tightly embracingthe jacket.

Ignition harness including a flexible 'manifold closed at one end, saidmanifold comprising a flexible seamless insulating jacket of oil andgasoline-resistant synthetic resin having high dielectric strength andwhich is toughand elastic throughout a wide range lof temperaturevariations, the jacket being provided at intervals along its length withfittings flxedly anchored thereto and designed for the attachment ofignition in the assembly, of thetrue conductors beyond the terminals ofthe latter, and insulation snugly filling the space within the sheathwhich is' not occupied by the conductors and dummies.'

9. An ignition harness of the kind including a flexible manifoldcomprising an assembly of individually insulated conductors housed in anelongate, flexible jacket of insulating material, the jacket havingilxedly anchored thereto a plurality of spaced fittings for theattachment of ignition wires; and the several conductors being ofdifierent lengths and each terminating at one of the respectivefittings, a thin flexible layer of metal interposed between theconductor assembly and the inner wall of the jacket, the jacket being ofl unitary, seamless construction and sufficiently flexible to permit itto be bent to arcuate contour.

10. An ignition harness of the kind including a flexible manifoldcomprising an assembly of individually insulated conductors housed in anelongate, flexible jacket of insulating material, the

jacket having iixedly anchored thereto a, plurality of spaced fittingsfor the attachment of ignition wires, and the several conductors beingoi' different lengths and each terminating at one of the respectivefittings, a thin flexible layer of metal foil interposed between theouter surface of the conductor assembly and the inner surface of thejacket, the jacket being a unitary, seamless mass of synthetic resinwhich is resistant to oil and gasoline.

11. An ignition harness comprising a manifold which is suflicientlyflexible to permit it to be manually bent and straightened at will, said`manifold having a plurality of flttingsspaced along it and designed forthe attachment of ignition wires, the manifold comprising a flexible,

seamless unitary jacket of oil-resistant insulate ing material, and anassembly of individually rinsulated conductors within the jacket, theseveral conductors being of different lengths and terminating at therespective fittings, and a flexible tube of thin metal embracing theconductor assembly and fitting snugly within the jacket.

l2. Ignition harness including a flexible mani braced by a jacket of oiland water-resistant insulating material, eachv lead having a connectorat'each end operative removably to unite the lead to one of the manifoldfittings and to a spark plug respectively, the metal sheathing of eachignition lead extending into said connectors.

13. Ignition harness including a flexible mani-` fold comprising aflexible, seamless insulating jacket of oil and water resistantmaterial, a hollow, flexible metal sheathing fitting snugly within saidjacket, insulated conductors within said vfsheathing, a plurality ofignition leads each including a flexible, seamless insulating jacket ofoil and water-resistant material, a hollow, flexible metal sheathingfitting snugly Within said jacket, and an insulated conductor withinsaid sheath, each ignition lead having a connector at one end by meansof which it may be removably secured to the manifold, and each of saidconnectors including means operative electrically to connect itsrespective conductor to one of the manifold conductors.

14. An ignition harness for use with internal combustion engines of theradial type, said harness comprisingan annular manifold designed to bearranged coaxially with the engine shaft and having a plurality oi'flexible spark plug leads, the manifold having a plurality oi! unitaryfittings spaced circumferentlally thereof and corresponding in number tothe number of spark plug leads, said fittings being designed to receivethe ends of the several spark plug leads, characterized in that each ofthe spark plug leads includes a flexible, seamless, insulating jacket o!an oiland waterresistant synthetic resin, a hollow flexible metal sheathntting snugly within said jacket, and a single insulated conductorwithin said sheath, each spark plug lead having a connector at one endby means of which it may -be removably connected both mechanically andelectrically to one of the fittings of the manifold and each of the saidspark plug leads having a connector at its opposite end for uniting itto a spark plug.

15. A normally substantially annular, flexible ignition manifoldcomprising a plurality of conductors encased within a unitary resilient,seamless jacket of oil-, gasolineand moisture-resistant synthetic resin,the Jacket having a plurality of circumlerentially spaced openings inits outer terminal of an ignition wire lead, and a thin,

flexible, tubular sheathing o! metal between the conductor and thejacket, said tubular sheathing constituting means to prevent radiointerference and to act as a condenser plate during high Irequencyheating of the Jacket-forming material.

HOWARD M. WILKOFF.

